American Airlines has joined the growing opposition to the U.S. Transportation Security Administration's new policy that allows passengers to carry small knives on planes.

In a letter to TSA Administrator John Pistole, American's Senior Vice President Will Ris wrote that the Fort Worth, Texas-based carrier agreed that it was "important" for the TSA to "regularly revisit its rules and regulations" and said American would "adhere fully" to TSA's policies, but added that he wanted to "voice American's concern" over the new change, which is scheduled to take effect on April 25.

"We encourage the TSA to reassess its proposed revisions to the prohibited items list," Ris wrote.

American is the third major U.S. airline to oppose the new policy since Pistole announced it last week, following in the footsteps of Delta Airlines and US Airways.

Delta, which is the world's second-largest airline, was the first to speak out against the policy.

In his letter last week, Delta's CEO Richard Anderson said although the Atlanta-based carrier had a strong relationship with the TSA, he disagreed with the agency's recent decision and shared the "legitimate concerns" of flight attendants. Anderson also pointed out that small knives have been banned from commercial planes for the past 11 years.

US Airways CEO Doug Parker also urged Pistole to "reconsider" the policy, writing in a March 11 letter, "US Airways fully supports the continuous review and amendment of TSA policies. We also understand and support the risk-based assessment employed by the TSA. However, this review and policy amendment process is most effective when it is conducted in a collaborative way with airlines and their flight crews."

"In particular, seeking input before implementing a change in policy that might place out flight attendants' safety at risk would have provided a more thoughtful path to the desired outcome of secure and safe air travel."

The new TSA policy will permit folding knives that do not lock and have blades that are 2.36 inches or less in length and are less than 1/2-inch wide inside the cabin. Novelty-sized and toy bats less than 24 inches long, billiard cues, ski poles, hockey sticks, lacrosse sticks and two golf clubs will also now be allowed in carry-on luggage.

The change, which was announced March 5, came after a TSA working group recommended that such items were not a security threat. The new policy will allow TSA security officers "to better focus their efforts on finding higher threat items such as explosives," the agency said in a statement.

The move will conform to international rules that allow small knives and sporting goods. Razor blades, ice picks, scissors and box-cutters -- like those used by the 9/11 terrorists -- will still be banned. Full-sized baseball bats will also remain on the prohibited carry-on list.